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3D barcodes to identify stolen valuables

DIAMONDS and valuable works of art could be protected against theft using a microscopic barcode that stores encrypted information about the provenance of the items, making ownership easy to prove if they are stolen.

The barcode, which takes the form of a cube 30 micrometres across, is being developed by a team at the National Physical Laboratory (NPL) at Teddington, near London. The cube is made of silicon coated with a 100-nanometre-thick layer of polymethyl methacrylate, a transparent plastic. It can be attached to hard surfaces using adhesive, or woven into the canvas of paintings.

To create the barcode an electron-beam lithograph drills 90,000 small squares into the plastic coat of each face at five different depths. The position and depth of each square is unique, so data can be encrypted using a key-based code and stored digitally. The cube is scanned line by line using an electron force microscope, which can detect differences in the depth of the squares. This scanning process takes around a minute, says Alexandre Cuenat, one of the team of researchers that developed the cube.

The technology has huge potential for storing information securely, says Cuenat. “You could get two copies of the bible, the King James version, on the sharp end of a pin.”

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However, in practice storing information on the provenance of an object would not require anything like this capacity.

The nanobarcode has three levels of security to protect objects against theft and counterfeit. First, thieves and fences are unlikely to realise that the item is protected. “You cannot see or feel the cube, even if you roll it between your finger and thumb,” says Cuenat. Second, most fraudsters are unlikely to have the specialist equipment to read or write the nanobarcode, and so will be unable to duplicate it. And finally the encryption will be practically unbreakable.

“Theoretically all codes can be broken,” says David Mendels, who led the NPL team. You just have to test all the different permutations. In this case, it would be possible to make the encryption extremely complex because of the cube’s high storage capacity. “You’d need a computer doing a million calculations a second and it would still take more than 187 billion years,” says Mendels. For day-to-day use, the encryption could be far less complex and still be virtually unbreakable, says Cuenat.

To break the code, it’d take a million calculations a second for 187 billion years

Once in mass production each device will cost about £1. Diamond traders have already approached the laboratory about the technology, which NPL hopes to license next year.

The nanobarcode could also protect other high-value items, such as bearer bonds and banker’s drafts.